Richards P, Ell S, Halliday D
Lancet. 1977 Jan 15;1(8003):112-4. doi: 10.1016/s0140-6736(77)91703-2.
Plasma valine and 13C-valine concentrations were measured in 2 healthy volunteers and 2 uraemic patients during and after a 3-hour intravenous infusion of the 13-c-labelled alpha-keto-acid analogue of valine. Plasma-valine increased by 23-43%. 13C-valine accounted for most of the early increase, but for less than 30% of the increase 1 hour after infusion. It was concluded that valine had increased by 2 mechanisms with different time courses. Initially, transamination of the infused ketoacid predominated, confirming directly for the first time that the essential aminoacid valine can be synthesised in-vivo both in health and uraemia. The previously unsuspected second mechanism was quantitatively more important but slower in ooperation; it may prove to be the key to understanding the metabolic effects of essential aminoacid precursors.
在两名健康志愿者和两名尿毒症患者中，于静脉输注13C标记的缬氨酸α-酮酸类似物3小时期间及之后，测定了血浆缬氨酸和13C-缬氨酸浓度。血浆缬氨酸增加了23%-43%。13C-缬氨酸占早期增加量的大部分，但在输注后1小时，其增加量占比不到30%。得出的结论是，缬氨酸通过两种具有不同时间进程的机制增加。最初，输注的酮酸的转氨作用占主导，首次直接证实必需氨基酸缬氨酸在健康状态和尿毒症状态下均可在体内合成。之前未被怀疑的第二种机制在数量上更为重要，但协同作用较慢；它可能是理解必需氨基酸前体代谢效应的关键。
